JPH02276480A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To improve a motor efficiency by providing a rotor with a cylindrical part to affect on the rotor. CONSTITUTION:An ultrasonic motor is constituted of a base plate 1, a disc type stator 2, a rotor 3 superposed through a friction material, an output shaft 8, a casing 10 and the like. A multitude of radial projections 2a is provided on the annular surface of the outer periphery of a stator 2, which is contacted with a rotor 3, while the rotor 3 is provided projectingly with a cylindrical part 3a on the outer periphery thereof. As a result, the cylindrical part 3a is pressed against the outer peripheral surface of the stator 2 at the radially outside of the stator 2 whereby a thrust may be increased.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an ultrasonic motor in which a rotor is pressed against a stator and the rotor is rotated by a traveling wave generated in the stator. It is designed to have a traveling wave act on it.

[Prior Art] An ultrasonic motor is manufactured by arranging a large number of piezoelectric elements on one side of a stator at a pitch of 1/2 the wavelength of the driving high-frequency voltage, or by polarizing piezoelectric elements in this manner. It will be done. A large number of piezoelectric elements are divided into two sets with an interval of λ/4, and a traveling wave is generated in the stator by applying high frequency voltages having a phase difference of 90° to each set.

The rotor, which is in pressure contact with the other surface of the stator, is rotated by the traveling wave.

The rotor is rotated by traveling waves generated in the stator, so
The rotor is brought into pressure contact with the stator so that traveling waves act on the rotor through the pressure contact surface.

In a conventional ultrasonic motor, a disc-shaped stator and a disc-shaped rotor are stacked on top of each other, and a traveling wave is applied only to one annular surface on the outer periphery of the stator and rotor.

[Problems to be Solved by the Invention] When a piezoelectric material is bonded along the outer periphery of a disc-shaped stator and a high-frequency voltage is applied to the piezoelectric material to generate a traveling wave, the stator has Traveling waves are generated not only on the outer peripheral surface of the stator in the radial direction, but also on the outer peripheral surface of the stator. For this reason, among the traveling waves generated in the stator, the traveling waves on the outer peripheral surface on the radially outer side that are not in contact with the rotor are not utilized, and the output efficiency cannot be sufficiently improved.

An object of the present invention is to press the rotor against the surface on the back side of the piezoelectric adhesive surface of the stator and the radially outer peripheral surface of the stator, so that traveling waves on two surfaces of the stator act on the rotor.

[Means for Solving the Problems] The ultrasonic motor of the present invention generates traveling waves by applying driving high-frequency voltages having a phase difference of 90 degrees to two sets of piezoelectric parts bonded to one surface of a stator. In an ultrasonic motor, the rotor, which is in pressure contact with the other surface of the stator, is rotated by a traveling wave. The rotor is characterized in that the rotor is provided with a second traveling wave operating surface that is in contact with an outer circumferential surface that is continuous from the back surface portion to the piezoelectric adhesive surface.

Further, the rotor is composed of a first rotor part having a disk shape and a second rotor part having a cylindrical part, the first rotor part is in pressure contact with the back side of the piezoelectric adhesive surface of the stator, and the second rotor part is connected to the stator. Traveling waves on two surfaces of the stator may be applied to the rotor by pressing against one outer circumferential surface on the radially outer side of the stator.

[Operation] In the ultrasonic motor of the above means, if a high frequency voltage is applied to the stator to generate a traveling wave, waves will be generated from two surfaces of the stator, the back side of the piezoelectric bonding surface and the outer circumferential surface on the outside in the radial direction. Traveling waves can be applied to the rotor, and the rotor can be rotated with a large thrust.

[Example] An embodiment of the present invention will be described with reference to FIG.

In the ultrasonic motor, a disc-shaped stator 2 is fixed on a substrate l, and a rotor 3 is stacked on top of the disc-shaped stator 2 via a friction material, and the rotor 3 is rotated by a traveling wave generated in the stator 2 as described later. It has become. In addition, stator 2
Alternatively, if friction is generated between the two by selecting the material of the rotor 3, there is no need for a friction material between the two. Further, a large number of radial protrusions 2a are provided on the annular surface of the stator at the outer peripheral portion where the stator 2 contacts the rotor 3, so that the amplitude of the traveling wave generated in the stator 2 can be increased.

The stator 2 is formed of an elastic body, and its outer periphery is apart from the substrate 1, and a piezoelectric material 4 is bonded to the surface of the stator 2 on the substrate 1 side. The piezoelectric body 4 is arranged in a ring shape, and is polarized into a plurality of piezoelectric elements with a pitch of 1/2 of the wavelength of the driving high-frequency voltage applied thereto, and the plurality of piezoelectric elements are polarized with a pitch of 1/2 of the wavelength of the driving high-frequency voltage applied thereto.
It is divided into two sets of piezoelectric parts separated by λ. And 2
By applying high frequency voltages having a phase difference of 90° to each of the piezoelectric parts of the set, a traveling wave of a wavelength of several wavelengths is generated in the stator 2.

In addition, in order for the rotor 3 to rotate in response to the traveling waves of the stator 2, it is necessary to bring the rotor 3 into pressure contact with the stator 2, and the rotor 3 is pressed toward the stator by the disc spring 7 via the friction material 6. It looks like this. The center-side base of the disc spring 7 is attached to the flange 8a of the output shaft 8, so that when the rotor 3 rotates, the output shaft 8 also rotates together via the disc spring 7. The output shaft 8 passes through each center hole of the rotor 3, stator 2, and substrate l, and the output shaft 8 has a bearing 9 provided on the base Mil and a thrust bearing 11 provided on the casing lO covering the upper part of the rotor 3. and is held.

The rotor 3 is disk-shaped and has approximately the same size as the stator 2, and has a cylindrical portion 3a protruding from its outer periphery. Then, the outer peripheral part of the disk part of the rotor 3 is pressed against the back side of the piezoelectric adhesive surface of the stator 2 (in this embodiment, the protrusion 2a), and the cylindrical part 3
a is brought into pressure contact with the outer circumferential surface of the stator 2 on the outside in the radial direction. Note that the pressure contact between the cylindrical portion 3a of the rotor and the outer peripheral portion of the stator 2 is such that a suitable pressure is generated by adjusting the fitting dimensions. Further, in order to increase the amplitude of the traveling wave generated on the radially outer outer circumferential surface of the stator 2, a large number of protrusions like the above-mentioned protrusions 2a may be provided on the radially outer outer circumferential surface of the stator 2.

Next, a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, the rotor is formed separately into a first rotor part 13a consisting of a disc part and a second rotor part 13b having a cylindrical part 14 on the outer periphery of the disc part. and stator 2
The first rotor portion 13a and the second rotor portion 1 are sequentially placed on the side.
3b were placed one on top of the other.

The cylindrical portion 14 of the second rotor portion is configured to contact the outer peripheral surface of the stator 2 without contacting the outer peripheral surface of the first rotor portion. Further, by pushing the second rotor portion 13b toward the stator side with a disk spring, the first rotor portion is also pushed and brought into pressure contact with the stator 2. A friction material 15 is arranged between the first rotor portion 13a and the second rotor portion 13b. The rotational force received by the first rotor portion 13a is transmitted to the second rotor portion 13b by the friction material 15.

Therefore, the first rotor portion 13a and the second rotor portion 13b
rotates as one. The second rotor portion 13b is connected to the rotating shaft 8 by a disc spring 7 as in the case of FIG.
The second rotor portion 13b transmits rotational force to the rotating shaft 8 via the disc spring 7. Further, a sliding member 16 is provided on the surface where the first rotor portion 13a contacts the stator 2.

Although this embodiment uses a disc-shaped stator and a rotor, the present invention can also be applied to a ring-shaped one for a camera.

[Effects of the Invention] The ultrasonic motor of the present invention has a cylindrical portion on the rotor, so that traveling waves can be applied to the rotor not only from the disk-shaped surface of the stator but also from the outer peripheral surface on the outside in the radial direction. , thrust is increased and motor efficiency is also improved.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of an ultrasonic motor according to the present invention, and FIG. 2 is a cross-sectional view of essential parts of an ultrasonic motor according to a second embodiment. l; Substrate 2; Stator 3; Rotor 3a;
Cylindrical part 13a; 10th-end part 13b: 2nd rotor part 14; Cylindrical part Applicant: Fuco Co., Ltd.
Kuaisin Seiki Co., Ltd.

Claims (2)

[Claims] (1) A traveling wave is generated by applying driving high-frequency voltages with a 90° phase difference to two sets of piezoelectric parts bonded to one side of the stator, and the rotor is pressed against the other side of the stator. In an ultrasonic motor that is rotated by a traveling wave generated in a stator, a first traveling wave operating surface is in contact with the back surface of the piezoelectric adhesive surface of the stator, and a first traveling wave operating surface is continuous from the back surface of the stator to the piezoelectric adhesive surface. An ultrasonic motor characterized in that the rotor is provided with a second traveling wave operating surface that is in contact with the outer peripheral surface of the rotor. (2) A driving high-frequency voltage with a 90° phase difference is applied to two sets of piezoelectric parts bonded to one side of the stator to generate a traveling wave, and the rotor pressed against the other side of the stator is In an ultrasonic motor that is rotated by a traveling wave generated in a stator, the rotor includes a first rotor part that receives the traveling wave in contact with a back part of the surface where a piezoelectric material is bonded to the stator, and a first rotor part that receives the traveling wave and the back part of the stator. 1. An ultrasonic motor comprising: a second rotor portion having a cylindrical portion that is in contact with an outer circumferential surface that is continuous with a piezoelectric bonding surface and receives a traveling wave, and the two rotor portions are arranged in an overlapping manner.